1. Field of the Invention
The present invention pertains to the art of rotary cutting machines and, more particularly, to a blade changing system for such a machine.
2. Discussion of the Prior Art
There exists various types of rotary cutting machines incorporating blades which need to be disconnected from a drive source in order to be periodically replaced or sharpened. For example, lawn mower blades should be sharpened or replaced at least yearly for peak effectiveness. In general, removing a lawn mower blade requires somehow retaining the blade from rotating while removing a retaining bolt used to drivingly interconnect the blade to an engine shaft. Removing a blade retaining bolt can often be difficult, and even dangerous. In fact, it is not uncommon for a retaining bolt to be over tightened or even rusted in place.
Regardless of the condition of the retaining bolt, it is necessary to prevent the blade from rotating while the high torque necessary to loosen the bolt can be applied, generally through the use of a wrench. Oftentimes, when changing a blade on a lawn mower, a block of wood, a brick or other handy object is initially placed between the blade and a discharge chute or other deck portion of the mower to prevent the blade from shifting as the bolt is being rotated. If the object slips, a cut or bruised hand may result. As an alternative, one can resort to utilizing leather work gloves for holding a blade secure while the bolt is loosened. This type of arrangement is not always effective as merely grasping the end of the blade with a gloved hand may not enable sufficient leverage to be developed to enable an overly tightened or rusted bolt to be removed. In addition, depending upon the condition of the blade and the quality of the gloves, this operation may be hazardous.
The problems associated with removing or installing a blade on a lawn mower can be further compounded by the ground level location of the blade. That is, the blade may only be limitedly visible and accessibe through the discharge chute unless the mower is run up on blocks, elevated on jacks, tilted backwardly or turned upside down. Although a push-type lawn mower can be fairly easily placed on its side to enhance access to the blade, the same is not possible in connection with a riding lawn mower. Oftentimes, even a heavy riding lawn mower is not elevated on blocks just to remove or install a blade. Instead the mower deck is simply elevated as far as possible which generally provides about 5 inches (approximately 12.5 cm) of visibility and working space for a person lying or crouching on the ground.
Regardless of the degree of accessibility of the blade, changing a blade can represent a dangerous endeavor, particularly due to the problem of adequately preventing the blade from undesirability rotating. One attempt to solve this problem of how to effectively hold a mower blade is described in U.S. Pat. No. 4,364,991 issued to Taylor. This patented arrangement involves the use of a specialty tool designed to be used in connection with a mower which is turned upside down. U.S. Pat. No. 4,956,905 issued to Davidson also addresses this problem in a similar manner by providing a dedicated tool for preventing undesirable rotation of the blade. In general, it is considered that providing a specialty tool is not cost effective or commercially viable, particularly due to the relatively infrequent need to work on the blades. However, providing a safe and effective system for changing a blade, i.e., either replacing a blade or removing it for sharpening and then reinstalling the same, is still considered an important issue to address in connection with lawn mowers, as well as other rotary cutting machines.
Based on the above, there exists a need in the art for a blade changing system which can be effectively used to either remove or mount a blade to a rotary cutting machine under a wide range of conditions, while not requiring a specialty tool.
The present invention is directed to a convenient and effective blade changing system wherein the blade is modified to directly cooperate with conventional tools which can be readily used to both retain the blade from rotating and to either tighten or loosen a fastening member for the blade. More specifically, the blade, which includes a generally centrally located opening through which a retaining bolt is adapted to extend, is formed with one or more polygonal shaped holes at a position longitudinally spaced from the central opening. The polygonal shaped hole is adapted to receive a hand tool commonly found in a standard tool set. In accordance with the first embodiment of the invention, the polygonal hole is square-shaped and sized to receive the head of either a conventional xe2x85x9cxe2x80x3 or xc2xdxe2x80x3 ratchet. In this arrangement, the drive of the ratchet is received in the polygonal hole and the handle end of the ratchet can be held by the user to prevent rotation of the blade while the threaded fastening member is rotated through the use of another wrench or the like. In accordance with a second embodiment, the polygonal hole is hexagonal in shape and is adapted to receive a standard Allen wrench. In a still further embodiment, the polygonal hole is configured to receive a Torx head-type wrench.
The present invention is particularly applicable for use in connection with installing or removing the blade of a lawn mower. When applied to this environment, the head of the ratchet can be readily inserted within the polygonal hole and a socket wrench or the like can be utilized to rotate a conventional retaining bolt used to drivingly interconnect the blade with an engine driveshaft of the mower. Regardless of the particular embodiment employed, no specialty tool is needed in connection with changing the blade, but rather only a couple of tools found in a standard tool box or kit are needed. In addition to avoiding the need for a specialty tool, the blade changing system of the present invention advantageously represents an arrangement which enables a user to readily provide a sufficient amount of counteractive force to prevent undesired rotation of the blade during removal or tightening of the retaining member.
Additional objects, features and advantages of the present invention will become more readily apparent from the following detailed description of preferred embodiments thereof when taken in conjunction with the drawings wherein like reference numerals refer to corresponding parts in the several views.